The present invention relates generally to a socket for a PGA (pin grid array package) to which the PGA package can be connected.
Conventionally, a socket for a PGA package as shown in FIG. 12 is well known in the art (See Japanese Unexamined Patent Publication (Kokai) No. Heisei 9-204969 and Japanese Unexamined Patent Publication (Kohyo) No. Heisei 10-508143 and the like, for example). The socket for the PGA package comprises a planar insulative housing 300 in which terminals are located in grid array fashion, and a cover 302 including pin insertion holes 301 formed in grid array fashion corresponding to the respective terminals. It is possible to slide the cover 302 on the insulative housing 300 by operation of a lever 303 and the like. Upon sliding the cover 302, pins of the PGA package respectively opposing to a contact piece of the respective terminals through the respective pin insertion holes 301 are adapted for engagement with the contact pieces.
The respective terminals mounted on the insulative housing include a solder tail extending from a bottom surface of the insulative housing and soldered to circuit pads of a printed circuit board. With the structure of the terminal, the structure as shown in FIG. 13 (see Japanese Unexamined Utility Model Publication (Kokai) No. Heisei 9-35838) and the structure as shown in FIG. 14 Publication (Kokai see Japanese Unexamined Utility Model No. Beisei 7-11787) are been well known in the art. With the structure of the terminal shown in FIG. 13, the reference numeral 310 denotes a contact piece, and the reference numeral 311 denotes a solder tail. Upon sliding the cover 302, a pin 320 is moved as indicated by arrow to contact with the contact piece 310. With the structure of the terminal shown in FIG. 14, the reference numerals 330 denote a pair of mutually opposing contact pieces, and the reference numeral 331 denotes a solder tail. Upon sliding the cover 302, the pin is moved between the mutually opposing contact pieces 330 to contact with the contact pieces 330.
With the typical structure of the terminal as set forth above, it is difficult to hold the terminal by the insulative housing in the structure of FIG. 13, since a moment is caused on the terminal when the pin of the package is engaged with the contact piece. Accordingly, this moment necessitates means such as provision of an anchor for engaging with the insulative housing in the direction of thickness of the terminal. Furthermore in the structure of FIG. 14, the terminal becomes relatively large upon being spread out, so that it lacks for process yield in case of stamping it from a resilient metal sheet. In conjunction therewith, it is difficult to make the terminal, since it is necessary to balance the resilience of the mutually opposing contact pieces.
The present invention has been worked out in order to solve the problems set forth above. Therefore, it is an object of the present invention to provide a socket for a PGA package for mounting terminals having a structure adapted for being firmly held on an insulative housing, and stably engaging with pins of the PGA package.
To accomplish the above-mentioned object, the present invention contemplates the provision of a socket for a PGA package including a planar insulative housing for mounting a plurality of terminals in grid array fashion, each said terminals having a solder tail projecting from one side surface of said insulative housing to be soldered to a printed circuit board, each said terminals may comprise:
a planar main portion extending in the direction of mounting to said insulative housing;
an anchor portion for engaging with said insulative housing on side edges of said main body;
a contact piece folded back into generally U-shaped configuration from a lower end of said main body and mutually opposing to said main body;
a solder tail extending toward said printed circuit board; and
said contact piece having a contact portion on an outside surface thereof for contacting with a pin of said PGA package.
According to the socket for the PGA package of the present invention, the terminal has a construction in which the contact piece is folded back into generally U-shaped configuration from the lower end of the main body to be opposed to the main body, and the contact portion engaging with the pin of the PGA package is formed on the outside surface of the contact piece. Accordingly, the contact piece with which the pin is engaged, is resiliently deformed about an U-shaped folded back portion in the direction of pivotal motion, and then this deformation force is transferred to the main body. Since the main body of the terminal can be mated with the inner wall of the terminal mounting portion of the insulative housing, it is possible to bear the deformation force by the whole area of the main body. As a result, it is possible to avoid causing the rotational moment on the terminal. Furthermore, the engagement between the pins and the contact pieces are also stabilized. Still further, in case of stamping the terminals (terminal blanks) from the resilient metal sheet, it is possible to arrange them for a small pitch to improve the process yield of materials, since each terminal has a construction in which the contact piece is folded back so as to be opposed to the main body.
The present invention will be understood more fully from detailed description given herebelow and from the accompanying drawings of the preferred embodiment of the present invention, which, however, should not be taken to be limitative to the invention, but are for explanation and understanding only.